The world famous house is open to the public for free every year as part of London's
architectural Open House Weekend. At other times of the year, visits for groups or
individuals can be arranged -contact us for fee details.

Such visits can include a talk and Q&A with the owner and founder of 3 Acorns Eco-audits
Donnachadh McCarthy FRSA

Donnachadh firmly believes that environmentalists should practice what they preach.
He has therefore converted his 1840’s Victorian terrace home into a retro-eco home.
It has solar electric panels, solar hot water panels, a rain-harvesting system, wood–burner,
wind-turbine and catalytic converter gas fire.

While it is essential to a low carbon home to use the home efficiently and ensure
all the basics such as insulation and energy efficient appliances are in place, certain
technologies can help.

Since 2003 the house has been a net exporter of electricity but in 2006/7 Donnachadh
achieve his dream of a not only a carbon neutral home but it actually become climate
positive i.e. it is carbon negative exporting more green electricity to the national
grid than it imports fossil fuels (gas)

The house was the first private home in London to export solar electricity from
the roof to London Electricity in 1997.

The 1.2 kW rated system was installed by Sundog Renewables. In 2006/7, the house
exported about 20% more electricity to the national grid than it imported.

Following EDF energy’s energetic lobbying of the UK government to promote a catastrophic
new generation of nuclear power stations, he is switching to exporting his green
electricity to Good Energy’s micro-generators scheme. Link to Good Energy's Homepage

The display on the right shows how much electricity the roof is producing, how
much is being imported or exported and how much the house is consuming. In 1997 the
system cost about £12,000. Solar electric systems today cost about the same but
produce twice as much electricity.

Solar Hot Water Panels and System

The solar hot water system was installed 2 years ago and supplies about 70% of
the household's hot water needs. The vacuum tube heat exchanger system was installed
by Southern Solar.

In summer the system produces far more hot water than is needed and the temperature
has to be regulated to prevent it from becoming too hot!

The system cost about £4,200 but a £400 grant from the LowCarbonBuilding Programme
and £500 from the local council brought the cost down.

Catalytic Converter Flueless Gas Fire

Unlike open coal-effect gas fires which are less than 20% efficient and traditional
radiant gas-fires which are about 65% efficient, flueless gas fires are extraordinarily
100% efficient.

Using an embedded catalytic converter, all of the gas is converted to heat, with
water being the only by product. This means that they are only useful in houses which
have central heating in the background or have a regularly used wood stove, as these
dry out the resulting condensation.

In my house, whilst very rarely used since the installation of the wood burner, it
acts as a very handy back-up system in case I am ill and cannot use the wood burner
or if in the house for a quick half hour before going out again and I need a burst
of heat.

They cost about £500 and I got mine from Burley’s.

Rainwater Collection Systems

The toilet in the bathroom and a designated tap are supplied by a simple gravity
fed rain-harvester system, which sits on the flat roof immediately above the bathroom.
It has supplied over 70% of the WC water needs since it was installed 9 years ago.
The main legal requirement for such systems is that the rainwater cannot mix accidentally
with mains-water and so special valves are required if you want the system to be
backed up with the mains.

The garden water needs are supplied from a tank that collects rain water from the
lower roof run-off. It is now quite old but still does the job, with its own tap.

Wind-Turbine

Three Acorns Retro-Eco House was the first house in London to gain planning permission
for a grid-attached building mounted domestic wind-turbine. It was installed in November
2005 but has not been a success to date.

It produced a recorded 16kWh last year, which is about £1.60 off the electricity
bill. There have been no noise complaints from neighbours, which is great, but there
is currently a vibration problem internally in the house.

StealthGen, the providers, continue to experiment with the product and the jury is
out as to whether such small urban wind-turbines will make a worthwhile contribution
in the future, even if some pessimists rule them out completely. It cost £2,800 installed.

Wood-burner

Last, but by no means least, 3 Acorns Retro-eco House has a wood burner in the open
plan living room/dining room/ kitchen area. This is by far the greatest contributor
to reducing the energy carbon footprint of the house. People often forget that electricity
consumption on average is responsible for only 30% of the average house’s carbon
footprint, whereas space and water heating account for the other 70%.

I got mine from UK manufacturer Clearview Stoves. It cost about £800 plus £2,000
for installation and new chimney flue.

Visits / Talks at 3 Acorns Retro Eco-House

Whilst not normally open to the public (except for the London Open House Weekend
Event in September), it is occasionally available for site visits/seminars for small
groups of council planners, councillors, energy consultants and other such interested
groups.